| 1 | =head1 NAME |
1 | =head1 NAME |
| 2 | |
2 | |
| 3 | AnyEvent::Fork::RPC - simple RPC extension for AnyEvent::Fork |
3 | AnyEvent::Fork::RPC - simple RPC extension for AnyEvent::Fork |
|
|
4 | |
|
|
5 | THE API IS NOT FINISHED, CONSIDER THIS A TECHNOLOGY DEMO |
| 4 | |
6 | |
| 5 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
| 6 | |
8 | |
| 7 | use AnyEvent::Fork::RPC; |
9 | use AnyEvent::Fork::RPC; |
| 8 | # use AnyEvent::Fork is not needed |
10 | # use AnyEvent::Fork is not needed |
| … | |
… | |
| 11 | ->new |
13 | ->new |
| 12 | ->require ("MyModule") |
14 | ->require ("MyModule") |
| 13 | ->AnyEvent::Fork::RPC::run ( |
15 | ->AnyEvent::Fork::RPC::run ( |
| 14 | "MyModule::server", |
16 | "MyModule::server", |
| 15 | ); |
17 | ); |
|
|
18 | |
|
|
19 | use AnyEvent; |
| 16 | |
20 | |
| 17 | my $cv = AE::cv; |
21 | my $cv = AE::cv; |
| 18 | |
22 | |
| 19 | $rpc->(1, 2, 3, sub { |
23 | $rpc->(1, 2, 3, sub { |
| 20 | print "MyModule::server returned @_\n"; |
24 | print "MyModule::server returned @_\n"; |
| … | |
… | |
| 372 | |
376 | |
| 373 | The default server used in the child does all I/O blockingly, and only |
377 | The default server used in the child does all I/O blockingly, and only |
| 374 | allows a single RPC call to execute concurrently. |
378 | allows a single RPC call to execute concurrently. |
| 375 | |
379 | |
| 376 | Setting C<async> to a true value switches to another implementation that |
380 | Setting C<async> to a true value switches to another implementation that |
| 377 | uses L<AnyEvent> in the child and allows multiple concurrent RPC calls. |
381 | uses L<AnyEvent> in the child and allows multiple concurrent RPC calls (it |
|
|
382 | does not support recursion in the event loop however, blocking condvar |
|
|
383 | calls will fail). |
| 378 | |
384 | |
| 379 | The actual API in the child is documented in the section that describes |
385 | The actual API in the child is documented in the section that describes |
| 380 | the calling semantics of the returned C<$rpc> function. |
386 | the calling semantics of the returned C<$rpc> function. |
| 381 | |
387 | |
| 382 | If you want to pre-load the actual back-end modules to enable memory |
388 | If you want to pre-load the actual back-end modules to enable memory |
| … | |
… | |
| 384 | synchronous, and C<AnyEvent::Fork::RPC::Async> for asynchronous mode. |
390 | synchronous, and C<AnyEvent::Fork::RPC::Async> for asynchronous mode. |
| 385 | |
391 | |
| 386 | If you use a template process and want to fork both sync and async |
392 | If you use a template process and want to fork both sync and async |
| 387 | children, then it is permissible to load both modules. |
393 | children, then it is permissible to load both modules. |
| 388 | |
394 | |
| 389 | =item serialiser => $string (default: '(sub { pack "(w/a*)*", @_ }, sub { unpack "(w/a*)*", shift })') |
395 | =item serialiser => $string (default: $AnyEvent::Fork::RPC::STRING_SERIALISER) |
| 390 | |
396 | |
| 391 | All arguments, result data and event data have to be serialised to be |
397 | All arguments, result data and event data have to be serialised to be |
| 392 | transferred between the processes. For this, they have to be frozen and |
398 | transferred between the processes. For this, they have to be frozen and |
| 393 | thawed in both parent and child processes. |
399 | thawed in both parent and child processes. |
| 394 | |
400 | |
| 395 | By default, only octet strings can be passed between the processes, which |
401 | By default, only octet strings can be passed between the processes, which |
| 396 | is reasonably fast and efficient. |
402 | is reasonably fast and efficient and requires no extra modules. |
| 397 | |
403 | |
| 398 | For more complicated use cases, you can provide your own freeze and thaw |
404 | For more complicated use cases, you can provide your own freeze and thaw |
| 399 | functions, by specifying a string with perl source code. It's supposed to |
405 | functions, by specifying a string with perl source code. It's supposed to |
| 400 | return two code references when evaluated: the first receives a list of |
406 | return two code references when evaluated: the first receives a list of |
| 401 | perl values and must return an octet string. The second receives the octet |
407 | perl values and must return an octet string. The second receives the octet |
| … | |
… | |
| 403 | |
409 | |
| 404 | If you need an external module for serialisation, then you can either |
410 | If you need an external module for serialisation, then you can either |
| 405 | pre-load it into your L<AnyEvent::Fork> process, or you can add a C<use> |
411 | pre-load it into your L<AnyEvent::Fork> process, or you can add a C<use> |
| 406 | or C<require> statement into the serialiser string. Or both. |
412 | or C<require> statement into the serialiser string. Or both. |
| 407 | |
413 | |
|
|
414 | Here are some examples - some of them are also available as global |
|
|
415 | variables that make them easier to use. |
|
|
416 | |
|
|
417 | =over 4 |
|
|
418 | |
|
|
419 | =item octet strings - C<$AnyEvent::Fork::RPC::STRING_SERIALISER> |
|
|
420 | |
|
|
421 | This serialiser concatenates length-prefixes octet strings, and is the |
|
|
422 | default. |
|
|
423 | |
|
|
424 | Implementation: |
|
|
425 | |
|
|
426 | ( |
|
|
427 | sub { pack "(w/a*)*", @_ }, |
|
|
428 | sub { unpack "(w/a*)*", shift } |
|
|
429 | ) |
|
|
430 | |
|
|
431 | =item json - C<$AnyEvent::Fork::RPC::JSON_SERIALISER> |
|
|
432 | |
|
|
433 | This serialiser creates JSON arrays - you have to make sure the L<JSON> |
|
|
434 | module is installed for this serialiser to work. It can be beneficial for |
|
|
435 | sharing when you preload the L<JSON> module in a template process. |
|
|
436 | |
|
|
437 | L<JSON> (with L<JSON::XS> installed) is slower than the octet string |
|
|
438 | serialiser, but usually much faster than L<Storable>, unless big chunks of |
|
|
439 | binary data need to be transferred. |
|
|
440 | |
|
|
441 | Implementation: |
|
|
442 | |
|
|
443 | use JSON (); |
|
|
444 | ( |
|
|
445 | sub { JSON::encode_json \@_ }, |
|
|
446 | sub { @{ JSON::decode_json shift } } |
|
|
447 | ) |
|
|
448 | |
|
|
449 | =item storable - C<$AnyEvent::Fork::RPC::STORABLE_SERIALISER> |
|
|
450 | |
|
|
451 | This serialiser uses L<Storable>, which means it has high chance of |
|
|
452 | serialising just about anything you throw at it, at the cost of having |
|
|
453 | very high overhead per operation. It also comes with perl. |
|
|
454 | |
|
|
455 | Implementation: |
|
|
456 | |
|
|
457 | use Storable (); |
|
|
458 | ( |
|
|
459 | sub { Storable::freeze \@_ }, |
|
|
460 | sub { @{ Storable::thaw shift } } |
|
|
461 | ) |
|
|
462 | |
|
|
463 | =back |
|
|
464 | |
| 408 | =back |
465 | =back |
| 409 | |
466 | |
| 410 | See the examples section earlier in this document for some actual |
467 | See the examples section earlier in this document for some actual |
| 411 | examples. |
468 | examples. |
| 412 | |
469 | |
| 413 | =cut |
470 | =cut |
| 414 | |
471 | |
| 415 | our $STRING_SERIALISER = '(sub { pack "(w/a*)*", @_ }, sub { unpack "(w/a*)*", shift })'; |
472 | our $STRING_SERIALISER = '(sub { pack "(w/a*)*", @_ }, sub { unpack "(w/a*)*", shift })'; |
|
|
473 | our $JSON_SERIALISER = 'use JSON (); (sub { JSON::encode_json \@_ }, sub { @{ JSON::decode_json shift } })'; |
|
|
474 | our $STORABLE_SERIALISER = 'use Storable (); (sub { Storable::freeze \@_ }, sub { @{ Storable::thaw shift } })'; |
| 416 | |
475 | |
| 417 | sub run { |
476 | sub run { |
| 418 | my ($self, $function, %arg) = @_; |
477 | my ($self, $function, %arg) = @_; |
| 419 | |
478 | |
| 420 | my $serialiser = delete $arg{serialiser} || $STRING_SERIALISER; |
479 | my $serialiser = delete $arg{serialiser} || $STRING_SERIALISER; |
| … | |
… | |
| 491 | undef $rw; undef $ww; # it ends here |
550 | undef $rw; undef $ww; # it ends here |
| 492 | |
551 | |
| 493 | if (@rcb || %rcb) { |
552 | if (@rcb || %rcb) { |
| 494 | $on_error->("unexpected eof"); |
553 | $on_error->("unexpected eof"); |
| 495 | } else { |
554 | } else { |
| 496 | $on_destroy->(); |
555 | $on_destroy->() |
|
|
556 | if $on_destroy; |
| 497 | } |
557 | } |
| 498 | } elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) { |
558 | } elsif ($! != Errno::EAGAIN && $! != Errno::EWOULDBLOCK) { |
| 499 | undef $rw; undef $ww; # it ends here |
559 | undef $rw; undef $ww; # it ends here |
| 500 | $on_error->("read: $!"); |
560 | $on_error->("read: $!"); |
| 501 | } |
561 | } |
| … | |
… | |
| 504 | $ww ||= AE::io $fh, 1, $wcb; |
564 | $ww ||= AE::io $fh, 1, $wcb; |
| 505 | }); |
565 | }); |
| 506 | |
566 | |
| 507 | my $guard = Guard::guard { |
567 | my $guard = Guard::guard { |
| 508 | $shutdown = 1; |
568 | $shutdown = 1; |
| 509 | $ww ||= $fh && AE::io $fh, 1, $wcb; |
569 | |
|
|
570 | shutdown $fh, 1 if $fh && !$ww; |
| 510 | }; |
571 | }; |
| 511 | |
572 | |
| 512 | my $id; |
573 | my $id; |
| 513 | |
574 | |
| 514 | $arg{async} |
575 | $arg{async} |
| … | |
… | |
| 516 | $id = ($id == 0xffffffff ? 0 : $id) + 1; |
577 | $id = ($id == 0xffffffff ? 0 : $id) + 1; |
| 517 | $id = ($id == 0xffffffff ? 0 : $id) + 1 while exists $rcb{$id}; # rarely loops |
578 | $id = ($id == 0xffffffff ? 0 : $id) + 1 while exists $rcb{$id}; # rarely loops |
| 518 | |
579 | |
| 519 | $rcb{$id} = pop; |
580 | $rcb{$id} = pop; |
| 520 | |
581 | |
| 521 | $guard; # keep it alive |
582 | $guard if 0; # keep it alive |
| 522 | |
583 | |
| 523 | $wbuf .= pack "LL/a*", $id, &$f; |
584 | $wbuf .= pack "LL/a*", $id, &$f; |
| 524 | $ww ||= $fh && AE::io $fh, 1, $wcb; |
585 | $ww ||= $fh && AE::io $fh, 1, $wcb; |
| 525 | } |
586 | } |
| 526 | : sub { |
587 | : sub { |
| … | |
… | |
| 640 | are queued and the jobs are slow, they will all run concurrently. The |
701 | are queued and the jobs are slow, they will all run concurrently. The |
| 641 | child must implement some queueing/limiting mechanism if this causes |
702 | child must implement some queueing/limiting mechanism if this causes |
| 642 | problems. Alternatively, the parent could limit the amount of rpc calls |
703 | problems. Alternatively, the parent could limit the amount of rpc calls |
| 643 | that are outstanding. |
704 | that are outstanding. |
| 644 | |
705 | |
|
|
706 | Blocking use of condvars is not supported. |
|
|
707 | |
| 645 | Using event-based modules such as L<IO::AIO>, L<Gtk2>, L<Tk> and so on is |
708 | Using event-based modules such as L<IO::AIO>, L<Gtk2>, L<Tk> and so on is |
| 646 | easy. |
709 | easy. |
| 647 | |
710 | |
| 648 | =back |
711 | =back |
| 649 | |
712 | |
| … | |
… | |
| 710 | |
773 | |
| 711 | Of course, this might be blocking if you pass a lot of file descriptors, |
774 | Of course, this might be blocking if you pass a lot of file descriptors, |
| 712 | so you might want to look into L<AnyEvent::FDpasser> which can handle the |
775 | so you might want to look into L<AnyEvent::FDpasser> which can handle the |
| 713 | gory details. |
776 | gory details. |
| 714 | |
777 | |
|
|
778 | =head1 EXCEPTIONS |
|
|
779 | |
|
|
780 | There are no provisions whatsoever for catching exceptions at this time - |
|
|
781 | in the child, exeptions might kill the process, causing calls to be lost |
|
|
782 | and the parent encountering a fatal error. In the parent, exceptions in |
|
|
783 | the result callback will not be caught and cause undefined behaviour. |
|
|
784 | |
| 715 | =head1 SEE ALSO |
785 | =head1 SEE ALSO |
| 716 | |
786 | |
| 717 | L<AnyEvent::Fork> (to create the processes in the first place), |
787 | L<AnyEvent::Fork>, to create the processes in the first place. |
|
|
788 | |
| 718 | L<AnyEvent::Fork::Pool> (to manage whole pools of processes). |
789 | L<AnyEvent::Fork::Pool>, to manage whole pools of processes. |
| 719 | |
790 | |
| 720 | =head1 AUTHOR AND CONTACT INFORMATION |
791 | =head1 AUTHOR AND CONTACT INFORMATION |
| 721 | |
792 | |
| 722 | Marc Lehmann <schmorp@schmorp.de> |
793 | Marc Lehmann <schmorp@schmorp.de> |
| 723 | http://software.schmorp.de/pkg/AnyEvent-Fork-RPC |
794 | http://software.schmorp.de/pkg/AnyEvent-Fork-RPC |
